A known approach to advanced technology fabrication of materials such as semi-conductor substrates, is to assemble a manufacturing facility as a “cleanroom.” In such cleanrooms, processing tools are arranged to provide aisle space for human operators or automation equipment. Exemplary cleanroom design is described in: “Cleanroom Design, Second Edition,” edited by W. Whyte, published by John Wiley & Sons, 1999, ISBN 0-471-94204-9, (herein after referred to as “the Whyte text” and the content of which is included for reference in its entirety).
Cleanroom design has evolved over time to include locating processing stations within clean hoods. Vertical unidirectional airflow can be directed through a raised floor, with separate cores for the tools and aisles. It is also known to have specialized mini-environments which surround only a processing tool for added space cleanliness. Another known approach includes the “ballroom” approach, wherein tools, operators and automation all reside in the same cleanroom.
Evolutionary improvements have enabled higher yields and the production of devices with smaller geometries. However, known cleanroom design has disadvantages and limitations.
For example, as the size of tools has increased and the dimensions of cleanrooms have increased, the volume of cleanspace that is controlled has concomitantly increased. As a result, the cost of building the cleanspace, and the cost of maintaining the cleanliness of such cleanspace, has increased considerably.
Tool installation in a cleanroom can be difficult. The initial “fit up” of a “fab” with tools, when the floor space is relatively empty, can be relatively straightforward. However, as tools are put in place and a fabricator begins to process substrates, it can become increasingly difficult and disruptive of job flow, to either place new tools or remove old ones. Likewise it has been difficult to remove a sub-assembly or component that makes up a fabricator tool in order to perform maintenance or replace such a subassembly or component of the fabricator tool. It would be desirable therefore to reduce installation difficulties attendant to dense tool placement while still maintaining such density, since denser tool placement otherwise affords substantial economic advantages relating to cleanroom construction and maintenance.
Solutions to the various needs may be found in vertically oriented fabricators which incorporate a cleanspace region. The multilevel fabricators may suggest further improvements both for fabricators which include a cleanspace region and those that do not.